When to plant in Rialto, CA
USDA Zone 10aRialto, California frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
Rialto's growing season is short at roughly -8 days, so succession planting is limited; lean on transplants over direct sowing for anything slow to mature. Heads up: the nearest complete-normals station is about 17 km from Rialto, so your yard's frost dates can differ — a low spot or a paved city center can shift them by a week. In zone 10a, frost is a minor factor for Rialto — most perennials thrive, and annual vegetables can go out early and stay late.
The average first fall frost in Rialto is now 10 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
RIVERSIDE CITRUS EXP · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Rialto’s own odds, recorded at RIVERSIDE CITRUS EXP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 12 | Feb 11 | Jan 1 | Nov 25 | Dec 13 | Jan 8 |
| 32°F | Feb 17 | Jan 10 | Dec 20 | Dec 11 | Jan 2 | Feb 7 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Nothing new to sow or transplant outdoors in the next few weeks — a seasonal lull. Check the full-year calendar below for the next window.
Full-year planting calendar
Each bar is the exact window to take a planting action in Rialto, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 19 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Rialto planting FAQ
When is the last spring frost in Rialto, CA?
Rialto's average last spring frost falls near January 10 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Rialto, CA?
Expect Rialto's first fall frost near January 2 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Rialto in?
Rialto is in USDA hardiness zone 10a. In zone 10a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Rialto?
Rialto has about -8 frost-free days — a short growing season — between the average last spring frost (January 10) and first fall frost (January 2).
When should I plant tomatoes in Rialto?
For Rialto, sow tomatoes indoors about November 15–November 29 and move the seedlings out around January 17, after the last spring frost.
Never miss a window in Rialto
An email when it’s time to start seeds, transplant, and sow — timed to Rialto’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Muscoy · 6 km
- Bloomington · 6 km
- Fontana · 7 km
- San Bernardino · 9 km
- Colton · 9 km
- Grand Terrace · 12 km
- Jurupa Valley · 15 km
- Loma Linda · 16 km
Frost dates recorded at RIVERSIDE CITRUS EXP, 17 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Rialto, CA — Frost Dates & Zone 10a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00047473. Retrieved from https://blissgarden.com/california/rialto.